R Notebook

library(tigris)
library(tidyverse)
library(tidyquant)
library(leaflet)
library(highcharter)
library(readxl)

states <- states(cb = TRUE, class = "sf")

Here’s a data import and wrangling exercise. Our purpose is to take an excel file of the housing price index (hpi) for the 50 states since 1975 and get into a format that can be used to visualize the data using ggplot, highcharter and leaflet.

For ggplot we’ll need to get this excel data into a data.frame or tibble with an appropriate date column.

For highcharter, we’ll need an xts object.

view(states_hpi)

Error in view(states_hpi) : could not find function "view"

states_wrangled_ggplot <- 
  states_hpi %>% 
  # remove confusing metadata
  slice(-508:-523) %>% 
  # add nice date column
  mutate(Date = seq(mdy('01/31/1975'), mdy('03/31/2017'), by = 'months')) %>%
  # remove the month column, move date column to be first
  select(Date, everything(), -Month) %>% 
  ##gather from wide to long format
  gather(state, hpi, -Date) %>%
  ##round hpi to four digits
  mutate(hpi = round(hpi, digits = 4)) %>%
  ##create a column called year and month by separating the date column
  #separate(date, into = c("year", "month"), sep = '-', convert = TRUE, remove = FALSE) %>% 
  ##create new column: hpa, hpa12, hpa3 etc.
  mutate(
         hpa = ((1+ (hpi-lag(hpi))/hpi)^12) - 1, 
         hpa12 = ((1+ (hpi-lag(hpi, 12))/hpi)^1) - 1, 
         hpa3 = ((1+ (hpi-lag(hpi, 3))/hpi)^4) - 1,
         hpi12 = lag(hpi, 12), 
         hpi12min = rollapply(hpi, 12, min, fill = NA, na.rm = FALSE, align = 'right'),
         hpi12max = rollapply(hpi, 12, max, fill = NA, na.rm = FALSE, align = 'right'))

head(states_hpa_leaflet$NAME)

[1] "Alaska"         "Alabama"        "Arkansas"       "American Samoa" "Arizona"       
[6] "California"    

# Build states map
statesPal<-colorNumeric(
  palette = "GnBu",
  domain = states_hpa_leaflet$hpa)
statesPopup <- paste0( 
                    states_hpa_leaflet$NAME,
                    "<br>Annual House Price Percent Change: ", 
                     states_hpa_leaflet$hpa, "%")
leaf_states <- 
  leaflet(states_hpa_leaflet) %>% 
  addProviderTiles("CartoDB.Positron") %>%   
  setView(-95, 40, zoom = 4) %>% 
  addPolygons(stroke = TRUE, color = "black", weight = .4, opacity = 1.0, 
              smoothFactor = 0.5, fill = TRUE, fillColor = ~statesPal(hpa), 
              fillOpacity = .8, layerId = ~STUSPS, popup = statesPopup)
leaf_states

states_hpi_highcharter <-
  states_hpi %>% 
  # remove confusing metadata
  slice(-508:-523) %>% 
  # add nice date column
  mutate(Date = seq(mdy('01/31/1975'),mdy('03/31/2017'), by = 'months')) %>%
  # remove the month column, move date column to be first
  select(Date, everything(), -Month) 
# We need to convert to xts before calling highcharter. 
states_hpi_xts <- states_hpi_highcharter %>% 
  as_xts(date_col = Date)

Error in parse(text = x) : <text>:1:8: unexpected symbol
1: United States
           ^

save(leaf_states, file = "leaflet_states.RDat")